The occurrence of pharmaceuticals, such as anti-inflammatories, antibiotics, antidepressants, antihistamines, and others in the effluents, is a very urgent problem and a big challenge for municipal wastewater treatment companies. Without special treatment, these microcontaminants are retained in discharged water and sewage sludge and this is a high threat to the environment. Cross-linked cationic starch (CLCS) adsorbents with various degrees of substitution (DS) of cationic groups were employed for the removal of diclofenac from aqueous systems. The equilibrium adsorption studies revealed that the driving force of adsorption was the electrostatic interaction between carboxylate groups of diclofenac and quaternary ammonium groups of CLCS. The sorption capacities of CLCS with DS of 0.21 (CLCS-0.21) and DS of 0.33 (CLCS-0.33) varied from 329 to 370 mg/g and from 597 to 684 mg/g, respectively. The release studies revealed that adsorbed diclofenac can be efficiently released into 0.25 mol/L NaCl solution. Adsorbent regeneration studies showed that after four regeneration cycles, the ability of CLCS-0.21 and CLCS-0.33 to remove diclofenac from the aqueous medium decreased by 6% and 3%, respectively. To conclude, CLCS-0.33 exhibited high absorption capacity and sustainability due to good recoverability properties and can be regarded as a promising microcontaminant adsorbent to be used in wastewater treatment processes.

The formation of water-insoluble complexes between chitosan (ChS) and caffeoylquinic acid (CQ) derivatives present in artichoke (AE) and green coffee bean (GCBE) extracts was investigated by the equilibrium adsorption method. The UPLC/HPLC analysis revealed that the phenolic compounds accounted for 8.1% and 74.6% of AE and GCBE respectively, and CQ derivatives were the predominant compounds. According to the applied Langmuir adsorption model, anionic compounds present in natural extracts were adsorbed onto the active centers of ChS, i.e., primary amino groups. The driving forces of adsorption were electrostatic interactions between cationic groups of ChS and anionic compounds of natural extracts. Chromatographic analysis revealed that not only CQ derivatives, but also other phenolic compounds of natural extracts were attached to ChS. The release of adsorbed compounds into different media as well as the bioactive properties of complexes were also studied. With the immobilization of bioactives onto ChS, increased and prolonged ABTS^•+ radical scavenging activity and decreased antifungal activity against Fusarium graminearum and Botrytis cinerea were observed compared to those of ChS. The findings of the current study highlight that the adsorption approach could be used to successfully prepare water-insoluble complexes of ChS and components of natural extracts with prolonged antioxidant activity.

Single-needle electrospinning and needle-free electrospinning were applied to fabricate cellulose acetate (CA) fibrous mats containing rosemary (RO), clove (CL) and thyme (TH) essential oils (EO) from binary or ternary solvent mixture solutions. When an acetone, dichloromethane, and dimethylformamide mixture was used as the solvent system, cylindrical nanofibers with an average diameter between 255 and 617 nm were obtained. Removing dimethylformamide from the spinning solution resulted in flattened microfibers with significantly larger diameters, varying from 1242 to 2939 nm. Furthermore, CA nanofibers loaded with RO, CL or TH essential oils with diameter distributions ranging from 55 to 176 nm, from 69 to 215 nm and from 44 to 291 nm, respectively, were produced from ternary solvent mixture solutions using needle-free electrospinning equipment. FTIR and TGA studies revealed the incorporation of essential oils into the fiber structure, and GC-MS was used to evaluate the release of bioactive components from fibrous mats. The electrospun nanofibers of CA/RO, CA/CL and CA/TH showed excellent antioxidant activity and antimicrobial properties against Escherichia coli, Pseudomonas aeruginosa and Listeria monocytogenes. In addition, the CA/CL fibrous mat was tested in the storage of fresh beef steaks.